docs(site): simplify features, how-it-works, and security sections

[Tam-Leal]

Summary

• Simplify Features section: one line per card, remove redundant tags
• Replace How it works step cards with a terminal-style spec panel (4 steps)
• Replace Security audit grid with a flat 4-line spec panel
• Improve readability: panel descriptive text uses --t2 at 13px instead of --t3 at 12px

Type of change

• Bug fix (user-visible)
• Feature (user-visible)
• Documentation / site only
• Tests, CI, or refactor (no user-visible change)

Checklist

• I ran npm test locally (required for code changes)
• I smoke-tested with npm start if dashboard.html or API behavior changed
• No secrets in commits (config.json tokens, .env, PATs)
• Updated CHANGELOG.md under Unreleased when the change is notable

Release

• No GitHub Release needed (default for tests, docs, CI-only)
• Release needed — describe why users should download a new build:

Test plan

• Serve site locally: npx serve site
• Check / sections: Features, How it works, Security
• Verify panel text is readable (contrast) on desktop and mobile
• Confirm links: Download in step 01, Hub section in feature card
• No em-dashes in copy